1. Field of the Invention
The invention relates to a method of manufacturing a semiconductor device, particularly an etching process and a process of removing a mask layer used in the etching process.
2. Description of the Related Art
A conventional method of manufacturing a semiconductor device includes an etching process for shaping a foundation insulation film, a metal layer, a semiconductor substrate and the like into a predetermined pattern using a photoresist layer as a mask and an ashing process for removing the photoresist layer used in the etching process.
A description will be given on an example of the conventional method of manufacturing the semiconductor device. As shown in FIG. 13A, back grinding is performed to the back surface of a semiconductor substrate 100 using a grinder to form a semiconductor substrate 100 having a predetermined thickness (100 to 150 μm, for example).
As shown in FIG. 13B, the back surface of the semiconductor substrate 100 is then etched with a predetermined etcher (a wet etcher or a dry etcher) to remove a mechanically damaged layer (about 30 μm) such as a rough portion of the back surface which is caused by the back grinding. Therefore, the back surface of the semiconductor substrate 100 is smoothed.
As shown in FIG. 13C, a photoresist layer 101 is then selectively formed on the back surface of the semiconductor substrate 100 by a photolithography. The semiconductor substrate 100 is dry-etched using the photoresist layer 101 as a mask. This etching process is performed in a vacuum chamber 111 of a dry etcher 110 as shown in FIG. 14A.
In FIG. 14A, the semiconductor substrate 100 is mechanically fixed to a stage 113 with a support member 112. FIG. 14B is a top plan view of the stage 113. The support member 112 is located on the edge of the semiconductor substrate 100, covering several millimeters. A portion covered by the support member 112 is not properly subjected to the etching, and thus removed finally as a non-product portion. An RF power supply 114 is connected with the stage 113. The RF power supply 114 is a high frequency power supply supplying power for generating plasma in the vacuum chamber 111.
An opening 102 is formed in the semiconductor substrate 100 by the etching using the photoresist layer 101 as a mask as shown in FIG. 13D. The opening 102 may be formed by a so-called Bosch process. The Bosch process is used to produce a deep vertical trench in the semiconductor substrate and consists of two periodically alternating processes, which are a plasma etching process in which a surface of the semiconductor substrate is plasma etched isotropically using a SF6 gas and a plasma deposition process in which carbon polymers are deposited as a protection film using a C4F8 gas on a sidewall of the trench formed by the plasma etching process.
The semiconductor substrate 100 is then taken from the vacuum chamber 111, and transferred into a chamber of an asher (a plasma asher, for example) (not shown). This asher is also basically provided with a vacuum chamber, a stage, a support member, an RF power supply and the like, similar to the dry etcher 100 described above. The photoresist layer 101 is then removed by a plasma ashing using, for example, oxygen plasma. A portion covered by the support member is not subjected to plasma and the ashing is not properly performed thereto, so that the ashing is performed again after the support member is shifted.
When the sidewall of the opening 102 is not formed smooth by the overhang phenomenon, the Bosch process or the like, the semiconductor substrate 100 is transferred from the asher to the etcher again and the sidewall of the opening 102 is etched for smoothing. This is necessary because that a homogeneous film deposition in the opening 102 is not achievable in the next step unless the sidewall is smooth. It is known that when the Bosch process is used for forming the opening 102 a rough wavy surface (scallops 103) is formed on the sidewall of the via hole 102 as shown in FIG. 13D. Therefore, it is necessary to perform the smoothing process particularly when the Bosch process is used.
The sidewall of the opening 102 is smoothed by the smoothing process as shown in FIG. 13E, and thereafter a homogeneous deposition is achieved in the opening 102.
In this manner, the etching process and the ashing process in the conventional method of manufacturing the semiconductor device are performed using the different dedicated apparatuses, respectively.
The relevant technique to this is described in the Japanese Patent Application Publication No. 2006-12889, for example.
As described above, the etching process and the ashing process are conventionally performed in the different dedicated apparatuses, respectively. Therefore, when the ashing process is to be performed after the etching process or the etching process is to be performed after the ashing process, it is necessary to transfer the semiconductor substrate 100 each time, thereby largely reducing production efficiency. Furthermore, a mechanical defect may occur in the semiconductor substrate 100 during the transfer.
Furthermore, since removing and setting works of the support member 112 are needed when the semiconductor substrate 100 is transferred between the etcher and the asher, it is difficult to locate the support member 112 in the exactly same position again. As described above, the portion covered by the support member 112 is not properly etched, and thus is not generally used as a product die. Therefore, when the support member is used for fixing the semiconductor substrate to the stage, the position of the support member is slightly shifted each time when the etching process and the ashing process are repeated, thereby degrading the reliability and the yield of the end product.
The invention is directed to a semiconductor device and a method of manufacturing the semiconductor device which achieve high reliability and high yield as well as increased production efficiency.